Turbine engines are utilized in various industries, such as the power-producing industry. These turbine engines, however, produce a stream of exhaust gas otherwise known as flue gas which contain components which are harmful to the atmosphere, such as oxides of nitrogen (NOx). To reduce the amount of these harmful components within the flue gas stream various procedures and apparatus have been developed. These processes typically involve passing the flue gas across a catalyst which has a reducing effect on the harmful components contained therein.
As part of these processes, often the introduction of cooling or cooling air is introduced into the flue gas stream. The cooling air acts to reduce the temperature of the flue gas to protect the effectiveness and efficiency of the subsequently utilized catalyst. The introduction of the cooling air, however, is in a non-homogeneous manner which can cause the flue gas stream to have non-uniform temperature zones, including zones of excessive high flue gas temperatures. These high flue gas temperature zones can ruin the effectiveness and longevity of the catalyst. Thus, it is critical that the cooling air be fully, i.e. homogeneously, mixed with the flue gas.
The prior art typically used for the introduction of cooling air into the flue gas stream includes the use of a rectangular-shaped grid having a series of pipes or jets for the introduction of the cooling air. This grid structure, however, has disadvantages. The flue gas discharge of the turbine engines used is circular in nature; and thus, create a swirling stream of flue gas. Introduction of the swirling stream into a rectangular-shaped cooling air grid is not effective in that parts of the grid do not come in contact with the flue gas stream while other parts of the grid are overwhelmed by the flue gas stream, thus simultaneously underwhelming and overwhelming the system.
Thus, there is a need for a cooling air system which is more effective and efficient for the introduction of cooling air into a swirling stream of flue gas.